Ultrastructural study of hormonally responsive striated duct cells in the mouse sublingual gland

In semithin sections stained with Heidenhain's iron hematoxylin, a few scattered granular cells were observed in the striated ducts (SDs) of sublingual glands (SLGs) of the mouse; they were seen normally only in the glands of adult males. However, it was shown by electron microscopy that many SD cells, other than these granular cells, had apical secretory granules, thus forming a granular striated tubule (named the GST in this study) in a portion of SD segments in both sexes. Sublingual GST cells had very small dense secretory granules near the apical surface, with the nucleus in the apical one-third to one-half of the cell; small Golgi apparatus; sparse rough endoplasmic reticulum (RER); and well-developed basal infoldings. However, some granular cells in male GSTs had abundant large dense secretory granules in the apical two-thirds of the cell, a basal nucleus, and modest basal infoldings. Such granular SD cells disappeared after castration in males. Granular SD cells could be induced in the GSTs of females by the injection of 5 alpha-dihydrotestosterone (DHT), triiodothyronine (T(3)), and/or dexamethasone (Dex); given simultaneously, these hormones acted synergistically in this induction. These results indicate a close similarity between the duct systems of the SLG and those of the submandibulan gland (SMG) of the mouse: granular SD cells of the GST in the SLG resemble GCT cells in the SMG in expressing some of the same biologically active polypeptides, in being sexually dimorphic, and in being under the same multihormonal regulation.